1. Field of the Invention
The present invention relates to a solid-state image pickup apparatus and a method for driving the solid-state image pickup apparatus.
2. Description of the Related Art
In recent years, a desire for increasing the number of pixels and a frame rate of a solid-state image pickup apparatus has been increased and a high output rate is demanded for the solid-state image pickup apparatus. As a technique for meeting such a desire, a solid-state image pickup apparatus of a digital output type having A/D (analog/digital) converters provided for every column has been developed. As circuits provided for every column, besides the A/D converters, there are CDS (Correlation Double Sampling) circuits, PGA (Programmable Gain Amplifier) circuits, memory circuits such as SRAMs, latch circuits, counter circuits, and the like. Those circuits become complicated and the number of necessary devices increases. As the number of devices increases, an occurrence probability of defect caused by a manufacturing step increases and a manufacturing yield decreases. Particularly, the circuit defects existing on a column basis become a linear defect, which causes a large deterioration in picture quality and causes the manufacturing yield to decrease. As a technique for allowing the circuits to be used even if there are defects of the column circuits, Japanese Patent Application Laid-Open No. 2009-213012 discloses such a technique that redundant column circuits are provided for an analog circuit and a defective column is replaced by them.
In the related art, a solution for the defect of the digital circuit, in particular, the memory circuit unit is not discloses. As also disclosed in the Japanese Patent Application Laid-Open No. 2009-213012, the redundant circuits will not be used in a non-defective chip and thus occupy a chip area in an inefficient manner.